1. Field
The present disclosure relates to a selective crystallization method and a laser crystallization apparatus used in the selective crystallization method, and more particularly, to a selective crystallization method which can improve the productivity of a crystallization process and a laser crystallization apparatus used in the selective crystallization method.
2. Description of the Related Technology
A substrate having thin-film transistors (TFTs) formed thereon is being used in active matrix displays. In particular, a TFT using a polycrystalline semiconductor film is capable of operating at high speed due to its high electron mobility compared to a TFT using an amorphous semiconductor film. Accordingly, a lot of research is being conducted on the technique of forming a semiconductor film with a crystalline structure by crystallizing an amorphous semiconductor film formed on an insulating substrate such as a glass substrate.
For crystallization, thermal annealing using furnace annealing, rapid thermal annealing, laser annealing, or a combination of these methods can be used. One substrate material applicable in crystallization is quartz, which has a superior heat-resisting property. However, quartz is expensive and hard to be processed into a large-sized substrate. This may explain the trend toward the use of a glass substrate. A glass substrate is economical, highly workable, and easy to be manufactured into a large-sized substrate. However, the glass substrate is susceptible to thermal deformation due to its low thermal resistance.